Please answer this It has been said that the Constitution is the "supreme law of the land" by this we mean?

In what two ways were the tang and song dynasties of china similar? they jointly built the grand canal. they were economically strong. they had weak military forces. they ruled for about 300 years. they discouraged buddhist ideas.

According to the federal regulations, which of the following studies meets the definition of research with human subjects? a study of twenty 4th grade classrooms in which researchers ask the schools to systematically vary the time of day reading is taught, and collect weekly assessments of reading comprehension for each child over a three-month period. the collection of data, by a playground designer hired by the superintendent of schools, about the physical dimensions of school playgrounds, presence of fencing, and the kinds of equipment currently provided. a feasibility study for implementing a year-round school program, focusing on economic issues such a facilities utilization and transportation costs. an analysis of aggregate data comparing statewide high school graduation rates provided by the state department of public instruction, using county tax information.

Me with this psychology homework, i’m struggling with it.